09 March, 2016

Overview of USGS National Map

USGS National Hydrography Dataset (NHD)

a.k.a. 'the blue lines'

  1. Primary purpose: to portray water on The National Map (non-directed network)
  2. Drainage network including rivers, streams, canals, lakes, ponds, coastline, dams, and streamgages
  3. Available in 1:1,000,000; 1:100,000 ('medium res'); and 1:24,000 ('high res' or 'local res').
  4. Used in conjunction with USGS Watershed Boundary Dataset, and 3D Elevation Program (3DEP) to create the NHD+

NHD and WBD FAQs

NHD

Access NHD

NHD+

  1. NHDPlus is an integrated suite of application-ready geospatial data sets that incorporate many of the best features of the National Hydrography Dataset (NHD), the National Elevation Dataset (NED), and the Watershed Boundary Dataset (WBD).
  2. NHD+ V2 available for 1:100,000 NHD; high-res NHD+ in development
  3. USGS and EPA contract Horizon Systems to build and maintain NHD+

How is the NHD+ made?

Some rules apply

  1. Reaches are directed, and each reach has 0 or 1 inlet and exactly 1 outlet
  2. NHD+ catchments are 1:1 for each internodal NHD reach
  3. To generate the NHD+, 'hydroenforcement' is applied: Water must flow along flow lines
  4. WBD is used to define the upstream boundary for NHD+ headwater catchments
  5. Digital elevation is used to define NHD+ catchment 'walls'

Access NHD+ and learn more

NHD and NHD+ discussion

Share your expertise

  1. How do you access NHD data?

  2. How do you access NHD+ data?